Apply bulk changes to multiple selected units
Select only the units that should share a change, then edit their common properties once so the change applies to every selected unit.
A bulk change made on a multi-selection applies to every selected unit, including units of different types (for example, changing height affects all selected cabinets and wardrobes together), so select only the units that should share the change.
When several units are selected, the strip light is added from the Common Properties Of All Selections entry in the Modify panel: open Modify Strip Light, add a strip light, choose its panel type, reference side and offset distance, then apply the change to all selected units at once.
When units are grouped and you want to edit them together, use "Select all from group" in the Modify menu to select the whole group, then change the shared option (for example the skirting options) once and it applies to every selected unit.